The formula H2O is also the molecular formula of water. For non-molecular substances such as table salt, we represent the composition with an empirical formula. Sodium chloride is represented by NaCl, meaning that sodium and chlorine ratio in sodium chloride is 1 to 1. Again, the subscript 1 is omitted.
By Phil Myers. The annelids include earthworms, polychaete worms, and leeches. All members of the group are to some extent segmented, in other words, made up of segments that are formed by subdivisions that partially transect the body cavity.Segmentation is also called metamerism.y Phil Myers. The annelids include earthworms, polychaete worms, and leeches. All members of the group are to some extent segmented, in other words, made up of segments that are formed by subdivisions that partially transect the body cavity.
Annelida â This group is probably the most recognized of the three worm classifications. Phylum Annelida includes some sea worms, but it is mostly comprised of segmented worms such as earthworms. Earthworms are also an unofficial broad classification of worms. Hundreds of different worm species in 16 families are considered earthworms. Earthworms are also divided into three subcategories depending on their ecosystem.